get request returns unexpected response

[monamana9000]

I am running an engine io server on port 3000:

import { createServer } from "node:http";
import { Server } from "engine.io";

const EMIT_INTERVAL_MS = 10_000;
const PACKETS_COUNT = 100;
const PACKET_SIZE = 100;

const httpServer = createServer();
const engine = new Server();

engine.attach(httpServer);

const packets = [];

for (let i = 0; i < PACKETS_COUNT; i++) {
  packets.push("a".repeat(PACKET_SIZE));
}

setInterval(() => {
  Object.keys(engine.clients).forEach((id) => {
    const client = engine.clients[id];
    packets.forEach((packet) => {
      client.send(packet);
    });
  });
}, EMIT_INTERVAL_MS);

function formatSize(val) {
  return Math.floor(val / 1024);
}

setInterval(() => {
  const mem = process.memoryUsage();
  console.log(
    `${Math.floor(process.uptime())}; ${formatSize(mem.heapUsed)}; ${formatSize(
      mem.heapTotal
    )}`
  );
}, 1000);

httpServer.listen(3000);

when I submit a get request on the server:
curl http://127.0.0.1:3000/engine.io/?EIO=4&transport=polling
I get this response:
{"code":0,"message":"Transport unknown"}

the engine io docs say I should get back a response which looks something like:

{
  "sid": "lv_VI97HAXpY6yYWAAAC",
  "upgrades": ["websocket"],
  "pingInterval": 25000,
  "pingTimeout": 20000,
  "maxPayload": 1000000
}

so what could possibly be wrong?

[darrachequesne]

Hi! I was not able to reproduce the issue with the code you provided:

"Transport unknown" suggests the transport query param is unknown (it can be either "polling" or "websocket"). Maybe an invalid character?

$ node -v
v24.10.0
$ npm ls engine.io
└── [email protected]

[monamana9000]

Hey, thank you for replying! I typed the url by hand in browser and got the handshake packet! Tho there seems to be an issue with the curl request, as it still returns {"code":0,"message":"Transport unknown"}

[darrachequesne]

Oh, I see! You need to quote the URL:

curl "http://127.0.0.1:3000/engine.io/?EIO=4&transport=polling"

[monamana9000]

ah...I should have paid attention to what I was actually putting in there :) thank you!

[monamana9000]

Just one last thing I wanted to ask you
this is a request I am sending off to the server but I was returned 400, do I need any other headers apart from these?
It's written in rust but the idea is clear

        let request = Request::builder()
            .uri("http://localhost:3000/engine.io/?EIO=4&transport=polling")
            .method(Method::GET)
            .version(Version::HTTP_11)
            .header(ACCEPT, "*/*")
            .body(Empty::<Bytes>::new())?;